University Park, Pa. — Shimin Liu, professor of energy and mineral engineering and the Thomas V. and Jean C. Falkie Mining Engineering Faculty Fellow at Penn State, received the Rossiter W. Raymond Memorial award from the Society of Petroleum Engineering (SPE) and the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) for the best paper published in AIME's fields. Liu was honored by SPE President Med Kamal and AIME President Elizabeth Holmes during the 2023 SPE Annual Technical Conference & Exhibition, held Oct. 16-18 in San Antonio, Texas.
The conference paper, “Carbonate Caprock–Brine–Carbon Dioxide Interaction: Alteration of Hydromechanical Properties and Implications on Carbon Dioxide Leakage,” focuses on the long-term integrity of carbon caprock, which is used to secure, seal and trap CO2 in subsurface formations as part of geological carbon sequestration for carbon management.
Liu said he was appreciative when discussing the award, touching on both the award’s legacy and co-author Guijie Sang, who recently earned his doctorate in energy and mineral engineering from Penn State and is now a research associate at the University of Strathcyde in the Scotland.
“I'm really happy to be selected along with Guijie, who is the next generation of researchers and engineers,” Liu said. “It really is an honor to think about the legacy of the award, especially of the namesake Rossiter W. Raymond, who is still spoken of so fondly, and know that is something we are now a part of.”
Sang said he never anticipated winning the award.
“It was a really big surprise, like finding out you won the lottery,” Sang said. “I really didn't expect this, but I was so thankful when we received the confirmation after so many years of hard work.”
Carbon storage, the process of capturing CO2 from energy systems and storing it within the selective and targeted Earth’s subsurface formations, is a growing field of study and an innovative approach to addressing climate change, the researchers said. Analysts project the carbon capture, use and storage market will quadruple to $14.2 billion by 2030.
According to Liu, the various methods and technologies have potential, but more research is required to ensure the storage process avoids hazards from excessive leakage, like contaminating aquifers or inducing a seismic risk. He said their research will help in understanding how stored carbon can alter the caprock structure within geological formations.
“Simply, there are two important things to consider with carbon sequestration,” Liu said. “One, you must find a site which can hold a large amount of CO2, and second, you must have extreme confidence, that when you store this carbon, it will not escape.”
The study focused on the carbon caprock, the researchers said, because it is one of the most common denominators among potential storage sites across the globe. Carbon caprock is often used as the sealing rock in the three main types of ideal geological formations: saline aquifers, depleted gas reservoirs and coalbed methane formations. Understanding how the caprock interacts with brine, the natural occurrence of mineral-rich ionized water along CO2 injection, is an essential piece of the puzzle in determining the caprock’s long-term integrity.
“If you have brine, that means you do have space available to store CO2,” Sang said.
Sang explained their approach to looking at the micro- and nano-scale pores included novel visualization imaging techniques and in-house lab experiments. In particular, they used small-angle neutron scattering to characterize the inaccessible pores compared to the overall total pores. By injecting their samples with a specialized methane fluid under high pressure they were able to distinguish accessible pores out of total porosity. They conducted mechanical and hydraulic property tests to see how carbon-brine interactions would influence the number of accessible pores.
“We're trying to provide some detailed characterization and detailed engineer design application parameters to understand the fracture behavior,” Sang said. “Understanding how potential pathways are formed via fractures helps us find ways to prevent leakage.”
The results showed the brine-carbon interactions increased porosity — the very thing they hope to prevent — because the rock became more permeable. It could eventually become a more conductive rock medium that could potentially lead to CO2 leakage.
“It’s a hard truth, but it’s an important step because it's direct evidence,” Liu said. “With this research, we can build a data chain to inform decision makers when considering future project implementation in formations with the carbonate as caprocks. This will help them appraise sites and find the most optimal location.”
Both Liu and Sang said they are interested in the potential of carbon sequestration, and they both are excited to continue looking at aspects of mineralogy in detail. They are particularly interested in kinetics to determine a richer understanding of how the interaction affects porosity and in finding the potential solution to ensure CO2 can be safely stored.
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